Human-Centric Interfaces for Ambient Intelligence

12.5 IMPLEMENTING PHYSICAL SELECTION

While for human beings selection unambiguously establishes a mental link between

the user and the target, the realization of such an association in the virtual world

is not trivial. Both user and target have a presence in the physical world—that is, the

user is a human being and the target is a physical object—but not necessarily in the

virtual world. Instead, there are digital counterparts in the virtual world that act as

the proxies of these objects. The virtual representation (presence) of the selection

means that these digital counterparts will exchange information. The amo unt of infor-

mation may vary—in some cases a single notification of selection may be sufficient; in

other cases complete addresses and even content may be passed. The commun ication

may have a single direction, either from pointer to target or vice versa, or be bidirec-

tional. The act of selection ends when the pointer and target counterparts have

exchanged sufficient information to establish an association. Note that actual knowl-

edge of selection may be on the side of the user or the target, or on both.

12.5.1 Implementing Pointing

Capturing the act of pointing requires the assistance of pointing devices and/or

pointing receptors that are able to detect the physical link established. A range of

technologies may be applied here, both active and passive. The actual action follow-

ing the selection may need different technologies and use different channels for

communication. Figure 12.4 is an overview of the components involved. Note that

some components may be combined in one device.

Pointer

Pointing Device

Mental Link

Physical Link

Target

Pointing Receptor

Target’s

Virtual

Presence

Pointer’s

Virtual

Presence

Virtual Link

FIGURE 12.4

Mental, physical, and virtual links in pointing.

12.5 Implementing Physical Selection 315